Test.ino

//Breadboard Test code
//ScrewDriver
//Spring 2019
const int AIN1 = 3;     //PD0  
const int AIN2 = 4;     //PD4
const int PWMA = 10;    //PD7
const int STBY = 8;     //PB5
const int Pot = A0;      
const int Direction=A2;        
void setup() {
  Serial.begin(9600);
  InitializeIO();       //Function to initailize IOs
  delay(200);                          
}

void loop() {
  digitalWrite(STBY,HIGH);
  int Dselect;
  Dselect=digitalRead(Direction); //Read state of pin to determine direction
  if (Dselect==0){
  digitalWrite(AIN1,LOW);
  digitalWrite(AIN2,HIGH);}
  else if (Dselect==1){
  digitalWrite(AIN1,HIGH);
  digitalWrite(AIN2,LOW);}
  int PotRead = 0;
  PotRead=analogRead(Pot);      //Read potentiometer
  int Motorspeed = 0;
  Motorspeed = map(PotRead, 0, 1023, 0, 255);
  analogWrite(PWMA,Motorspeed); //Write motorspeed at the PWM pin
  Serial.println(Dselect);
  delay(2);
    }

IO.ino

//This file contains intializations for all the IO pins
void InitializeIO() {
  pinMode(3,OUTPUT);
  pinMode(4,OUTPUT);
  pinMode(8,OUTPUT);
  pinMode(10,OUTPUT);
  pinMode(A0,INPUT);
  pinMode(A2,INPUT);
};